As a conventional brake device, one example of such brake device has been known in in FIG. 1 of Patent Document 1, in which the brake device is shown. The brake device includes a drive hydraulic pressure chamber (dynamic pressure chamber 7) for driving a master piston (dynamic pressure piston 9), a high pressure source (dynamic pressure source 5) connected to the drive hydraulic pressure chamber and accumulating hydraulic pressure of brake fluid delivered from an electric pump by pumping, a low pressure source (reservoir 6) connected to the drive hydraulic pressure chamber and reserving pressure lower than the pressure accumulated in the high pressure source and a pressure modulating valve 4 adjusting communication between the dynamic pressure source 5 and the reservoir 6 and the dynamic pressure chamber 7 in response to a command from an electronic control device 3 to control output hydraulic pressure, wherein the hydraulic pressure in the drive hydraulic pressure chamber is adjusted by the hydraulic pressure in both high and low pressure sources.